A PACLOBUTRAZOL-RESISTANCE ( PRE ) gene family, consisting of six genes in Arabidopsis thaliana , encodes a group of helix-loop-helix proteins that act in the growth-promoting transcriptional network. To delineate the specific role of each of the PRE genes in organ growth, we took a reverse genetic approach by constructing high order pre loss-of-function mutants of Arabidopsis thaliana . In addition to dwarf vegetative growth, some double or high order pre mutants exhibited defective floral development, resulting in reduced fertility...

Multiple-allele-inherited male sterility (MAMS) is important in Chinese cabbage (Brassica rapa L. ssp. pekinensis) breeding, but the molecular mechanisms leading to male sterility are poorly understood. In this study, we cloned a novel gene, BrSKS13, that is differentially expressed in fertile and sterile flower buds of Chinese cabbage. BrSKS13 is most similar to Arabidopsis thaliana AT3G13400 (SKS13) and encodes a predicted 61.87 kDa protein with three cupredoxin superfamily conserved domains in the multicopper oxidase family...

After several decades of research, dynamics and patterns of mating system in floral evolution remain incompletely understood, especially with regards to strategies that combine both outcrossing and selfing, as frequently recorded in the genus Campanula. Data about temporal and spatial dynamics of secondary pollen presentation are still scarce in literature: we investigated them using Campanula medium (Campanulaceae) as case study. Experimental pollinations were conducted under natural conditions, to characterise the breeding system of this species...

To study the breeding system and pollination characteristics of Gleditsia sinensis, we observed the development of flower development and the processing of pollination, and determined the pollen viability and stigma acceptability by TTC and benzidine-hydrogen peroxide method and detected its breeding system using OCI value, P/O ratio and artificial pollination.The results showed that: ①G. sinensis are racemes, divided into bisexual inflorescences (only a small amount of inactive pollen) and male inflorescences (occasionally a few bisexual flowers), flowers hermaphrodite...

In flowering plants, sexual reproduction is actively regulated by cell-cell communication between the male pollen and female pistil, and many species possess self-incompatibility systems for the selective rejection of self-pollen to maintain genetic diversity. The Brassicaceae self-incompatibility pathway acts early on when pollen grains have landed on the stigmatic papillae at the top of the pistil. Extensive studies have revealed that self-pollen rejection in the Brassicaceae is initiated by an S-haplotype-specific interaction between two polymorphic proteins: the pollen S-locus protein 11/S cysteine-rich (SP11/SCR) ligand and the stigma S receptor kinase (SRK)...

Arabinogalactan proteins (AGPs) are hyperglycosylated members of the hydroxyproline-rich glycoprotein (HRGP) superfamily and are widely distributed throughout the plant kingdom. In Oryza sativa (rice), the gene expression and biological function of AGPs only have received minimal research attention. Here, we used qRT-PCR to detect the expression patterns of OsAGP genes in various organs, and found that six genes were preferentially expressed in panicles, three genes were specifically expressed in anthers, and one gene in the stigma...

Self-incompatibility (SI) is a genetic mechanism in hermaphroditic flowers that prevents inbreeding by rejection of self-pollen, while allowing cross- or genetically diverse pollen to germinate on the stigma to successfully fertilize the ovules. In Brassica, SI is initiated by the allele-specific recognition of pollen-encoded, secreted ligand (SCR/SP11) by the stigmatic receptor kinase S-locus receptor kinase (SRK), resulting in activation of SRK through phosphorylation [1-3]. Once activated, this phospho-relay converges on intracellular compatibility factors, which are immediately targeted for degradation by the E3 ligase, ARC1, resulting in the pollen rejection response [4, 5]...

Pollen viability affects the probability that a pollen grain deposited on a plant's stigma will produce a viable seed. Because a mature seed is needed before a gene flow event can occur, pollen viability will influence the risk of escape for genetically-engineered (GE) crops. Pollen viability was measured at intervals for up to two hours following removal of the pollen from the anthers. It was quantified at three temperatures and for different alfalfa varieties, including both conventional and Roundup Ready (RR) varieties...

Self-fertilization has recurrently evolved in plants, involving different strategies and traits and often loss of attractive functions, collectively known as the selfing syndrome. However, few traits that actively promote self-fertilization have been described. Here we describe a novel mechanism promoting self-fertilization in the Brassicaceae species Erysimum incanum. This mechanism, which we called "anther rubbing," consists of autonomous, repeated, and coordinated movements of the stamens over the stigma during flower opening...

Cockroaches have rarely been documented as pollinators. In this paper we examine whether this is because they might be inefficient at pollination compared to other pollinators. Clusia blattophila, a dioecieous shrub growing on isolated rocky outcrops in French Guiana, is pollinated by Amazonina platystylata cockroaches and provides a valuable system for the study of cockroach pollination efficiency. We examined the species composition of the visitor guild and visitation rates by means of camcorder recordings and visitor sampling...

Self-incompatibility is one of the most common mechanisms used by plants to prevent self-fertilization. In the Brassicaceae, the inhibition of self-pollen is triggered right at the stigma surface by interaction of two highly polymorphic self-recognition proteins that are encoded by tightly linked genes of the S-locus haplotype: a receptor protein kinase displayed at the surface of stigma epidermal cells and its small diffusible ligand that is localized in the outer coat of pollen grains. It is the specific interaction between receptor and ligand encoded in the same S haplotype that determines specificity in the rejection of self-pollen...

With the origin of pollination in ancient seed plants, the male gametophyte ("pollen") began to evolve a new and unique life history stage, the progamic phase, a post-pollination period in which pollen sexual maturation occurs in interaction with sporophyte-derived tissues. Pollen performance traits mediate the timing of the fertilization process, often in competition with other pollen, via the speed of pollen germination, sperm development, and pollen tube growth. Studies of pollen development rarely address the issue of performance or its evolution, which involves linking variation in developmental rates to relative fitness within populations or to adaptations on a macroevolutionary scale...

Field experiments were conducted for 2 years to examine the response of stigma in two different pollination systems, viz., CMS line (MJA5) and open-pollinated variety (Pusa Bold) of Indian mustard (Brassica juncea), to varying weather conditions created by different sowing dates. The CMS line MJA5 (female) with its male line in 8:2 (A:R) row ratio, and Pusa Bold in an isolated field were sown on 21st of October, 30th of October, and 18th of November in 2 consecutive years in North Indian condition. Temporal differences in sowing provided differed weather conditions during flowering, which resulted in variations in the duration to attain the peak flowering stage...

Background: The male fitness pathway, from pollen production to ovule fertilization, is thought to strongly influence reproductive trait evolution in animal-pollinated plants. This pathway is characterized by multiple avenues of pollen loss which may lead to reductions in male fitness. However, empirical data on the mechanistic processes leading to pollen loss during transport are limited, and we therefore lack a comprehensive understanding of how male fitness is influenced by each step in the pollination process...

Self-Incompatibility (SI) is a genetically controlled mechanism that prevents self-fertilisation and thus encourages outbreeding and genetic diversity. During pollination, most SI systems utilise cell-cell recognition to reject incompatible pollen. Mechanistically, one of the best-studied SI systems is that of Papaver rhoeas (poppy), which involves the interaction between the two S-determinants, a stigma-expressed secreted protein (PrsS) and a pollen-expressed plasma-membrane localised protein (PrpS). This interaction is the critical step in determining acceptance of compatible pollen or rejection of incompatible pollen...

Reproductive isolation, the key process to prevent interspecific hybridization and keep the completeness and independence of species, is crucial to the formation and maintenance of biodiversity. The forming steps, methods and intensities of reproductive isolation between different species are not completely the same. Literatures on reproductive isolation between species provide valuable evidence for speciation and its maintenance. Flowering phenology, flowering-visiting insects, and pollen-stigma compatibility were observed for Ligularia virgaurea and L...

Plant reproduction relies on transfer of pollen from anthers to stigmas, and the majority of flowering plants depend on biotic or abiotic agents for this transfer. A key metric for characterizing if pollen receipt is insufficient for reproduction is pollen limitation, which is assessed by pollen supplementation experiments. In a pollen supplementation experiment, fruit or seed production by flowers exposed to natural pollination is compared to that following hand pollination either by pollen supplementation (i...

Honey bees (Apis mellifera L. (Hymenoptera: Apidae)) are effective pollinators of many crops but are thought to be inefficient in pollinating blueberries (Vaccinium corymbosum L.) due to their inability to buzz pollinate. Nonetheless, commercial growers rent honey bee hives for pollination, resulting in the dominance of honey bee workers visiting flowers during bloom. The objective of this study was to examine where on the honey bee pollen is carried and how it is transferred from flower to bee to the stigma of other flowers...